SummaryMany recombination, DNA repair and DNA replication mutants have high basal levels of SOS expression as determined by a sulAp-lacZ reporter gene system on a population of cells. Two opposing models to explain how the SOS expression is distributed in these cells are: (i) the 'Uniform Expression Model (UEM)' where expression is evenly distributed in all cells or (ii) the 'Two Population Model (TPM)' where some cells are highly induced while others are not at all. To distinguish between these two models, a method to quantify SOS expression in individual bacterial cells was developed by fusing an SOS promoter ( sulAp ) to the green fluorescent protein ( gfp ) reporter gene and inserting it at att l l l l on the Escherichia coli chromosome. It is shown that the fluorescence in sulAp-gfp cells is regulated by RecA and LexA. This system was then used to distinguish between the two models for several mutants. The patterns displayed by priA , dnaT , recG , uvrD , dam , ftsK , rnhA , polA and xerC mutants were explained best by the TPM while only lexA (def) , lexA3 (ind -) and recA defective mutants were explained best by the UEM. These results are discussed in a context of how the processes of DNA replication and recombination may affect cells in a population differentially.

A survey was developed and distributed to the Massachusetts cranberry grower community in 1999 to identify biological, educational, social and political barriers to the adoption of available integrated pest management (IPM) practices. The response rate for the 450 growers who received the survey was 54%. Approximately 80% of respondents claimed to practice IPM frequently and 16% identified themselves as occasional practitioners. Most growers practiced IPM because they agreed with IPM philosophy (80%) and believed it had environmental benefits (73%). Ninety-two percent agreed that more IPM-related research and education programs would encourage them to adopt practices they are not currently using. A significant percentage of respondents used multiple IPM component practices, with practices involving monitoring and detection of pests along with judicious use of pesticides being most common. Factor analysis was used to condense 104 potential responses to 22 factors, which were then used as predictors with six demographic variables (IPM adoption, education level, age, experience, farm size and work status). Demographic factors influenced a grower's tendency to incorporate IPM into routine farm activities. Full-time, highly experienced growers in charge of large operations tended frequently to use more IPM practices than less experienced growers who worked part-time and managed smaller farms. A large proportion of respondents agreed that IPM can reduce pesticide residues in food (92%) and the environment (96%), and can help to preserve beneficial insects (96%). Although many growers held the perception that IPM can pose measurable economic risk (and subsequently act as a barrier to adoption), growers appeared to feel less strongly about the economic benefits than potential environmental ones.

Dodders (Cuscuta spp.) are parasitic plants that threaten the sustainability of many crops. Because this parasite is very adept and successful from biological and ecological perspectives, a single control strategy is unlikely to provide sufficient economic control. Dodder (C. gronovii) is a particularly serious pest in commercial cranberry (Vaccinium macrocarpon) production. Multiple viable strategies must be integrated and tailored into a weed management plan to provide acceptable control. The key to sustainable management of this serious pest will require a combination of chemical and cultural approaches, supported by understanding the complicated nature of dodder biology. Research from small fruit production systems like cranberry into the biology of dodder (e.g., germination patterns, host preference, use of plant growth regulators) may provide insights that could ultimately be useful for other crop system management plans. This paper will present the current knowledge base for integrated management of dodder in cranberry as well as highlight relevant research from other crops and potential topics for future research

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Dodder is a serious parasitic weed of cranberry bogs. Investigations were undertaken to determine if applications of sand to cranberry bogs might be useful as a control strategy for dodder. Sand is regularly applied to bogs as a cultural practice. In greenhouse studies, applications of sand reduced the seedling emergence, but did not affect survival time of dodder seedlings. At least 2.5 cm of sand was needed to reduce the emergence of dodder seedlings. Sanding may be used as part of a program consisting of combinations of multiple management methods directed toward the control of dodder. In addition, potential exists for using sand as a nonchemical means for obtaining some control, should present herbicidal control methods become unavailable.